Stacked photosensitive elements



Sept. 14, 1965 J. E. CAMPBELL ETAL 3,206,311

STACKED PHOTOSENSITIVE ELEMENTS Filed May 5. 1961 PHOTOSENSITIVE LAYER8.9. SILVER HALIDE l0 SUPPORT A l4 &\\\\\\\ 5 com-me COMPRISING PRIMARYAMIDES DERIVED FROM HIGHER FATTY ACIDS kvwww ORNEYS United States Patent3,206,311 STACKED PHOTOSENQTIVE ELEMENTS John E. Campbell, Needham, andJohn J. Dennis, In,

North Quincy, Mass., assignors to Polaroid Corporation, Cambridge, Mass,a corporation of Delaware Filed May 5, 1961, Ser. No. 108,051

- 7 Claims. (Cl. %-87) This invention relates to photographic elementsor material and more particularly to elements having low w efficients ofstatic friction.

A principal object of the present invention is to provide photographicelements such as, for example, photosensitive elements having a sliplayer or coating which possesses a very low friction coeflicient.

Another object of the invention is to provide photographic elementshaving a slip coating of the above type which does not adversely affectphotosensitive coatings or layers when in direct and tight con-tacttherewith.

Still another object of the invention is to provide photographicelements having a slip coating comprising an organic polymeric materialand one or more primary, str-aightch-ained amides having at least 8carbon atoms.

A still further object of the invention is to provide photographicelements having a slip coating comprising an organic polymeric materialand a mixture of primary, straight-chained amides having 18 carbonatoms.

Still another object of the invention is to provide a method oflubricating all types of photographic material or elements.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationand order of one or more of such steps with respect to each of theothers, and the products possessing the features, properties and therelation of elements which are exemplified in the following detaileddis-closure and the scope of the application of which will be indicatedin the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the drawing wherein a photographic product is disclosed,in exaggerated cross section, illustrating the back or slip coating ofthe present invention.

It is well known that problems of static, friction, and the like arefrequently encountered during the manufacture or during the use .ofcertain photographic materials such as, for example, photosensitiveelements. In order to substantially reduce or eliminate these problemsso as to facilitate handling and other operations as applied to suchphotographic materials or products, it has generally been the practiceto employ, for example, anti-static coatings, slip or lubricatingcoatings or some other expedient such as interleaving or the like.

P-hotosens-itive elements present particular problems. For example, inmany instances, a photosensitive element in strip form is tightly woundfor insertion into cassettes, magazines or the like, or a plurality ofphotosensitive elements of a predetermined size are tightly stacked inparallel relationship in a magazine or housing such as shown, forexample, in US. Patents Nos. 2,435,- 720, 2,495,111, 2,930,299,2,946,270, 2,978,971 and many others. In such instances, aphotosensitive layer is in direct and intimate contact with the backingof a photosensitive element. Thus, in addition to reducing static andfriction, any backing coat or layer carried by a photosensitive elementto be used as above must not otherwise adversely affect thephotosensitive layer with which it is in contact. In the presentinvention there are provided photographic products such asphotosensitive elements having on one surface thereof, e.g., the back, athin con- "ice tinuous layer or coating comprising an organic polymericmaterial and at least one primary, straight-chained amide derived from afatty acid having at least 8 carbon atoms. In one embodiment of theinvention, said coating comprises a cellulose plastic such as acellulose ester or cellulose ether and a mixture of amides containing 18carbon atoms and, more particularly, a mixture of octadecanamide,9-octadecenamide and 9,IZ-Octadecadienamide. It has been found that suchcoatings not only substantially reduce static and friction, but also donot transfer off to produce undesirable effects or cause fogging ordesensitization of photosensitive layers or emulsions.

Referring now to the drawings there is illustrated a photosensitiveelement comprising .a base or support-10, a photosensitive layer 12carried by one surface or side of support 10, and .a backing or slipcoating 14 carried by the other side of support 10. The support 10 maybe comprised of any of the flexible sheet materials generally used forfilm base, including paper, organic plastics such as cellulose esters,e.g., cellulose acetate etc., and the like. In some instances there maybe employed a supp-ortfltl which is opaque to light actinic to thephotosensitive layer 12 or which includes a layer, for example, slipcoating 14, which is opaque to actinic light.

The photosensitive layer 12 may comprise any of the materials usuallyemployed in photography including, for example, the silver halides orother photosensitive heavy metal salts capable of having a developa-blelatent image formed therein by exposure to actinic light, the ferricsalts and the di-azonium compounds. In one form, photosensitive layer orstratum 12 contains one or more of the silver halides, of which silverchloride, silver bromide and silver iodide are examples, dispersed on asuitable protective colloid material, for example, gelatin, agar,albumin, casein, a cellulose such as carboxymethyl cellulose, a vinylpolymer such as polyvinyl alcohol or a linear polya-mide such aspolyhexamethylene adipamide. Examples of specific formulations ofconventional emulsions suitable for use are described in T. T. Baker,Photographic Emulsion Technique, American Photographic PublishingCompany, Boston, 1948, Chapter IV.

It should be pointed out that although only the use of onephotosensitive layer is illustrated, such as may be utilized for theproduction of a black-and-white or'mon-ochromatic image, it is to beunderstood that more than one can be employed, such as may be the casewhere a multichromatic image is desired. For obtaining color imagesthereby may be contained in separate layers or in one or more silverhalide layers, for example, various other components such assensitizers, couplers, dyes and the like. A detailed description of thevarious possible arrangements of photosensitive layers or other layersassociated therewith or of the compositions thereof for the productionof black-.and-white or color images need not be given here since suchare so well-known to the art.

The slip or back coating 14 comprises an organic polymeric material andat least one primary, straight-chained amide derived from a higher fattyacid. The amides of the present invention and .a suitable organicfilm-forming polymeric material such as, for example, a cell-ulosicplastic, are preferably applied from certain solvents or media incontrolled amounts to support 10 so as to form thereon a thin backinglayer or coating.

The amides which may be utilized in back coating 14 may be genericallydepicted by the following formula:

where R represents a straight-chained aliphatic group containing fromabout 7 to 17 carbon atoms. Among the amides which may be employed incoating 14-, mention may be made of decanamide, dodecan-amide,tetradecancoating 14 may contain only .a single amide such as 9-octadecenamide or it may contain a mixture of amides such "asioctadecanamide, 9-0ctadecenamide and 9,12- octadeoadiena'mide. Onepreferred amide mixture of the invention comprises, by weight, about 6percent oc-tadecanamide, about 91 percent oct-adecenamide and about 3percent octadecadienamide. Other mixtures such as those of the followingapproximate compositions may alsojbe utilized: (1) 3% hexadecanamide,93% octa-decanamide and 4% 9-oct-adecenamide; (2) 22% hexadecanalmide,75% octadecan-amide and 3% 9-octaclecenamide; and (3) 8% octanam-ide, 7%decanarnide, 49% dodecanamide, 17% tetradecanamide, 9% hexadecana'mide,6% 9-octadecena'mide and 2% each of octadecana-mide and 9,12-octadecadienamide.

Coating 14 in addition to the preferred amide also contains an organicfilm-forming polymeric or resinous material. Among the suitablepolymeric materials men- "tion may be made on the cellulosic plasticssuch as the cellulose ethers and esters, e.g., cellulose acetatebutyrate,

ethyl cellulose, cellulose nitrate and the like. The polymeric'materialserves as a binder for the amide or amides employed sov as to prevent orsubstantially reduce the transfer of amide from the coating. Moreover,in instances where the support is of paper, the polymeric materialprevents undesirable penetration of amide into the paper. The quantityof polymeric material employed depends upon many factors such as, forexample, the

type of coating machine, the nature of the amide or amides utilized, thecoating thickness desired and the like. Thus, the quantity of polymericmaterial may be varied considerably.

Coating 14 may be formed by applying to support a suitable solution ordispersion, e.g., an emulsion containing the desired polymeric materialand amide or amides. The amides of the present invention are soluble inacetones, esters, alcohols, and other materials and thus .may be easilyapplied in-solution. Preferably the solvent or combination of solventsemployed for dissolving the amide or amide mixture is also preferably amutual solvent for the film-forming polymeric material utilized.

For a further understanding of the invention, reference "should be hadto the following non-limiting examples:

Example I solvent removed. Wherein the frictional value of the untreatedpaper was 0.36,. paper treated or coated with the above compositionreduced this static value to 0.11- 0.15. Thus the coefficient offriction of the photosensitive element was reduced more than 50%.Moreover,

it was found that there was no transfer of the amides from the coatingto produce undesirable effects nor did the coating cause fogging ordesensitization of a photosensitive layer when in intimate and prolongedcontact therewith. Film pack tests wherein a plurality of treatedphotosensitive elements were tightly stacked in parallel relationship ina magazine resulted in the easy and smooth withdrawal of one element ata time, in proper sequence, from the magazine.

Example II Other satisfactory backing or slip coats for paper basephotographic elements were obtained from the following compositions:

Ethyl cellulose "grams" 3.2 Preferred amide mixture do 1.2 Isopropylalcohol cc 59.2 Ethyl acetate cc 36.4 Cellulose nitrate grarns 3.8Preferred amide mixture do 1.2 Isopropyl alcohol cc 57.0 Ethyl acetatecc 36.0

Example III In addition to the above coating compositions, a dispersionor emulsion composition such as set forth below may also be employed.

To an emulsion comprising 15.0 grams of cellulose acetate butyrate, 34.0cc. of ethyl acetate, 13.5 cc. of toluene, 2.5 cc. of Tween 20(trademark of Atlas Powder Co. for an emulsifying agent comprising asorbitan monolaurate polyoxyalkylene derivative) and 24.0 cc. of water,there was added a composition comprising 1.0 gram of the preferred amidemixture and 10.0 cc. of ethyl acetate. The emulsion produced from theabove materials was then coated upon a paper base and dried. Wherein thepaper had an initial static coefiicient of friction of 0.36, the coatingproduced from the above emulsion reduced this value to 0.22.

It should be noted that an opacifying agent such as a suitable dye,e.g., red or black, or pigment such as carbon black may be added to anyof the above compositions so as to obtain a coating which is opaque tolight. Thus, for example, coating 14 may comprise cellulose acetatebutyrate, the preferred amide mixture and carbon black.

The concentration or quantity of the amide or amides in the coatingcomposition may be varied considerably. When employing the preferredamide mixture, concentrations of between about A of 1 percent and about2 percent have been found to be satisfactory. Concentrations of thepreferred amide mixture on the order of about 1.0 to about 1.2 percentof the total coating composition such as illustrated in the examplesprovide excellent back coatings.

Although the invention has been described in connection withphotosensitive elements, it is also applicable to other photographicstructures. For example, in many film pack structures, the leader ofeach photosensitive element is so arranged that a substantial portionthereof is in direct and tight contact with a photosensitive layer andmovable thereover. It has been found that the co- ,eificient of frictiontherebetween can be substantially reduced and satisfactory resultsobtained when the contacting surface of a leader which is generallyconstructed of paper is provided with the slip coatings of the presentinvention.

Since certain changes may be made in the above process an vention hereininvolved, it is intended that all matter contained in the abovedescription or shown in the accompanying drawing shall be interpreted asillustrative and not in a limiting sense.

What is claimed is:

1. A photographic product comprising a plurality of a photosensitiveelement and movable thereover, said first contact surface of ea-ch saidphotosensitive element being in contact with another contact surfaceprovided by at least one of (a) the second contact surface of another ofsaid photosensitive elements and (b) a third contact surface provided bya surface of a paper leader, one of said second and third contactsurfaces having coated thereon, as a slip coat, a continuous layercomprising a mixture of (a) at least one primary, straight-chained amidecontaining from about 8 to 18 carbon atoms and (b) a polymer selectedfrom the group consisting of cellulose acetate butyrate, ethyl celluloseand cellulose nitrate, said polymer substantially preventing transfer ofsaid amide from said slip coat, and said slip coat substantiallyreducing the coefficient of friction between said first contact surfaceand said other contact surface.

2. A photographic product as defined in claim 1, wherein said slip coatis coated on said second contact surface of said photosensitive element.

3. A photographic product as defined in claim 1, wherein said slip coatis coated on said surface of said paper leader providing said thirdcontact surface.

4. A photographic product as defined in claim 1, wherein said polymer iscellulose acetate butyrate and said amide is a mixture ofoctadecanamide, 9-octadecenamide and 9,12-octadecadienamide.

5. A photographic product as defined in claim 4, wherein said mixturecomprises about 6% of octadecan- 6 amide, about 91% of 9-octadecenamideand about 3% of 9,12-octadecadienamide.

6. A photographic product as defined in claim 5, wherein said mixturecomprises between about of 1% and about 2% of the total compositionutilized to produce said slip coat.

7. A photographic product as defined in claim 1, wherein said slip coatincludes carbon black.

References Cited by the Examiner UNITED STATES PATENTS 1,957,912 5/34Seel 117-157 2,070,991 2/37 Hund 106-186 2,103,640 12/37 Richter 117-1572,235,516 3/41 Cornwell.

2,258,609 10/41 Hill 96-84 2,311,073 2/43 Nadeau et al. 9684 2,415,6312/47 Galley 96-85 2,432,864 12/47 Dimsdale et al. 96-85 2,588,765 3/52Robijns 96-87 2,732,305 1/56 Richman 96-84 2,751,309 6/56 Baxter 96-78XR 2,773,769 12/56 Goldschein 96-84 2,898,805 8/59 Solow et al. 96-78 XR3,021,229 2/ 62 Morgan.

NORMAN G. TORCHIN, Primary Examiner.

PHILIP E. MANGAN, Examiner.

1. A PHOTOGRAPHIC PRODUCT COMPRISING A PLURALITY OF PHOTOSENSITIVEELEMENTS BEING TIGHTLY STACKED IN PARALLEL RELATIONSHIP AND POSITIONEDWITHIN A HOUSING, SAID PHOTOSENSITIVE ELEMENTS BEING REMOVABLE FROM SAIDHOUSING ONE ELEMENT AT A TIME, EACH OF SAID PHOTOSENSITIVE ELEMENTSCOMPRISING A SUPPORT CARRYING AT LEAST ONE PHOTOSENSITIVE SILVER HALIDELAYER ON ONE SIDE OF SAID SUPPORT TO PROVIDE A FIRST CONTACT SURFACE,THE OTHER SIDE OF SAID PHOTOSENSITIVE ELEMENT PROVIDING A SECOND CONTACTSURFACE, EACH OF SAID PHOTOSENSITIVE ELEMENTS HAVING A PAPER LEADER INDIRECT AND TIGHT CONTACT WITH THE FIRST CONTACT SURFACE OF APHOTOSENSITIVE ELEMENT AND MOVABLE THEREOVER, SAID FIRST CONTGACTSURFACE OF EACH SAID PHOTOSENSITIVE ELEMENT BEING IN CONTACT WITHANOTHER CONTACT SURFACE PROVIDED BY AT LEAST ONE OF (A) THE SECONDCONTACT SURFACE OF ANOTHER OF SAID PHOTOSENSITIVE ELEMENTS AND (B) ATHIRD CONTACT SURFACE PROVIDED BY A SURFACE OF A PAPER LEADER, ONE OFSAID SECOND AND THIRD CONTACT SURFACES HAVING COATED THEREON, AS A SLIPCOAT, A CONTINUOUS LAYER COMPRISING A MIXTURE OF (A) AT LEAST ONEPRIMARY, STAIGHT-CHAINED AMIDE CONTAINING FROM ABOUT 8 TO 18 CARBONATOMS AND (B) A POLYMER SELECTED FROM THE GROUP CONSISTING OF CELLULOSEACETATE BUTYRATE, ETHYL CELLULOSE AND CELLULOSE NITRATE, SAID POLYMERSUBSTANTIALLY PREVENTING TRANSFER OF SAID AMIDE FROM SAID SLIP COAT, ANDSAID SLIP COAT SUBSTANTIALLY REDUCING THE COEFFICIENT OF FRICTIONBETWEEN SAID FIRST CONTACT SURFACE AND SAID CONTACT SURFACE.